1. Field of the Invention
This invention is in the field of galvanic electrochemical cells used to convert chemical energy into electrical energy (e.g. fuel cells) or store electrical energy as chemical energy (e.g., batteries and flow cells) having means to provide relative motion between an element and an electrolyte—including means for creating Taylor Vortex Flows (TVF) and Circular Couette Flows (CCF) in the electrolyte (U.S. Class 429/69,72; Int. Class H01M-2/38, 2/12) to promote generation of alternating current electricity.
2. Description of Related Art
Two methods of converting chemical energy into electrical energy are a) burning fuel (e.g., coal, natural gas, liquid hydrocarbons) with oxygen to create heat in a motor or engine used to provide mechanical power to an electrical generator or alternator and b) promoting a reduction-oxidation (redox) reaction in a chemical cell that generates an electrical current in a circuit external to the cell. The former method can provide direct current (DC) or alternating current (AC); however, the process is Carnot ΔT temperature-limited by materials and therefore efficiency of burning fuel for electrical energy is low in accordance with the Second Law of Thermodynamics. The latter method is also constrained by the Second Law of Thermodynamics (in that entropy change, TΔS, at chemical and thermal equilibrium can approach H, enthalpy—G, Gibbs free energy) and therefore can be highly efficient; but, until now, has been restricted to DC electrochemical reactors. This Specification describes novel galvanic electrochemical cells for generating alternating current electricity.
Galvanic electrochemical cells include fuel cells used to convert chemical energy into electrical energy through use of catalysts as well as batteries and flow cells used to store electrical energy in chemical form through reversible reactions (secondary cells) or irreversible reactions (primary cells) promoted by faradaic materials that support reduction-oxidation (redox) chemical reactions. Galvanic cells produce electricity through spontaneous reactions and are distinguished from electrolytic electrochemical cells that require electrical energy to initiate and sustain electrochemical reactions (e.g., electrowinning) that are usually irreversible. Also, electrolytic cell electrodes do not contain faradaic or catalytic materials.
As used here, the term galvanic materials includes faradaic materials that chemically participate in redox reactions and catalytic materials that support redox reactions but are not chemically altered as a result. In general, galvanic cells comprising, in one case, a pair of electrodes comprising faradaic materials that promote two-phase (metal-electrolyte) reactions or, in another case, three-phase (catalyst-fuel or oxidizer-electrolyte) electrochemical reactions. These reactions separate electrons or ions from atoms or molecules, which then become energized ions (e.g., protons). The electrons travel from one electrode to the other electrode through an external electrical circuit where work is performed while the ions travel through a fluid electrolyte between the electrodes.
Patent publications and patents of Halbert Fischel enumerated above—as well as prior art references cited in them—describe examples of galvanic cells that generate DC electricity. Other disclosures well known to persons of ordinary skill in the art teach how to connect DC sources to external circuits, here called ‘inverters’, containing at least one electrically-reactive-impedance component (e.g., a capacitor or an inductor such as a transformer) for storing electrical or magnetic energy to obtain AC electricity. These inverters usually contain a switch located in a circuit between the galvanic cell and the reactive-impedance component to interrupt the flow of DC current to the reactive-impedance component. Early on, such switches comprised a vibrating reed supporting an electrical contact that periodically touched a fixed contact in a component then called a ‘vibrator’. More recently, circuit interruption has been accomplished with solid-state components such as thyristors, silicon-controlled-rectifiers (SCRs) and integrated gate transistors such as metal-oxide-silicon-field-effect-transistors (MOSFETs).
One principal disadvantage of vibrator, thyristor, SCR, MOSFET and similar switches is that they waste galvanic cell energy by generating undesirable alternating harmonic currents (generally at odd multiple frequencies of the switch frequency) that do not contribute to output AC and must be dissipated as heat energy. These alternating harmonic currents may also combine to create high peak voltages, currents and energies that require more-costly or additional inverter components to dissipate. Some inverters waste energy when needing to commutate their switches to change states (e.g., by turning one switch to on to force a complementary switch to turn off). In the end, inverter design contains tradeoffs between conversion efficiency and manufacturing costs. This invention focuses on changing galvanic cell architecture and method of operation in order to simplify or remove a need for the switches and the inverters and to improve efficiency of generating alternating current electricity from chemical fuel sources.